(a) Technical Field
The present invention relates to a system and method of detecting fuse disconnection of a DC-DC converter. More particularly, the present invention relates to a system and method that detects disconnection of an input fuse of a low-voltage DC-DC converter (LDC) without adding a separate hardware in a green vehicle such as an electric vehicle or hybrid electric vehicle.
(b) Background Art
Green vehicles that may replace existing internal-combustion engine vehicles have been actively developed due to a high oil prices, control of carbon dioxide, etc. Both electric vehicles (EV) driven by an electric motor and hybrid electric vehicles (HEV) driven by an internal-combustion engine and an electric motor as a driving source have become commercialized or on their way to commercialization according to manufacturers.
EVs and HEVs typically include a high-voltage battery (main battery) mounted therein. The high-voltage battery (main battery) is a power source that supplies electric power to an electric motor (traction motor) that acts as a driving source. In addition, EVs and HEVs also typically have a charging device that charges a battery, a motor control unit (MCU) (i.e., a type of controller) including an inverter that drives an electric motor (hereinafter, referred to as a ‘driving motor’), etc.
Here, the MCU converts DC voltage into three-phase power through the inverter by controlling the driving of switching elements in the inverter, so that each phase current can be applied to the driving motor. The MCU includes an input capacitor connected to a DC link terminal in the inverter so as to be charged by the voltage supplied from the high-voltage battery.
A battery management system (BMS) monitoring the state of the high-voltage battery is mounted in the EV and HEV. The BMS collects battery state information on the temperature, voltage, charging/discharging current and state of charge (SOC) of the battery, and provides the collected battery state information to another controller in the vehicle so that the battery state information can be used to control the vehicle.
Particularly, the BMS manages the state of the battery to maintain a certain level or more by verifying the state of the battery, and prevents the lifespan of the battery from being shortened by the degradation of the durability of the battery. In addition, the BMS notifies a vehicle control unit (VCU) (e.g., a different controller) performing integration control of information on the SOC of the battery, so that the traveling of the vehicle can be performed in consideration of the state of the battery.
A power relay assembly (PRA) is provided on a high-voltage circuit connecting the high-voltage battery to the DC link terminal of the MCU (inverter). The PRA performs switching so that the power of the high-voltage battery is selectively supplied to the vehicle. The PRA includes a main relay that is a main power contact, a precharge relay mounted on the circuit bypassing the main relay, a pre-charge resistor, etc. The on/off driving of the relays is controlled according to a control signal output by the BMS.
In addition, a hybrid control unit (HCU), an auxiliary battery (low-voltage battery) supplying a low-voltage electric load, a low-voltage DC-DC converter (LDC) performing power conversion between the high-voltage battery and the auxiliary battery, etc. are mounted in the vehicle. Here, the HCU is the highest level controller that collects various kinds of information in the vehicle and performs a control of the vehicle by communicating with other controllers such as the MCU or the BMS. Basically, the controllers in the vehicle execute the control of the vehicle while transmitting/receiving information therebetween through a communication network.
Meanwhile, the LDC charges the auxiliary battery by transforming DC power supplied from the high-voltage battery in an ignition on-state and an on-state of the main relay. An input fuse is connected to a primary input terminal to which the power of the high-voltage battery is input in the LDC. In a case where the input fuse is disconnected, the operation of the LDC is impossible due to disconnection of the input terminal of a high-voltage power source. In this case, the charging of the auxiliary battery is impossible, and vehicle operation is difficult due to discharging of the auxiliary battery.
In an ordinary vehicle, a fuse is connected to various kinds of electrical components including the LDC through a wiring harness. In addition, a hardware element for detecting disconnection of the fuse is provided to each electrical component. For example, the disconnection of the fuse is detected by adding a separate analog circuit such as a sensing circuit or a comparator comparing voltages between both ends of the fuse.
However, the amount of room in a vehicle into which a component can be inserted is restricted, and thus packaging of the components is severely restricted. Particularly, when the analog circuit (comparator or sensing circuit) is added to the LDC in which the fuse is mounted on a printed circuit board (PCB) in an electric field component, the analog circuit occupies a large area on the PCB, and costs are incurred due to the addition of the circuit.